Description

This report provides a detailed analysis of brain activity recorded during a single EEG session. It is designed to make EEG data interpretation more accessible while providing sufficient depth for meaningful analysis. Includes:

power spectra and band power calculations for each channel, along with topographic maps that show how different brainwave frequency ranges (theta, alpha, beta, etc.) are distributed across the scalp.
changes in frequency band power over time, offering insight into how brain activity fluctuated throughout the session
spatial distribution of the signal showing which regions on the cortex these signals originated

Understanding EEG Frequency Bands

EEG signals are commonly divided into frequency bands, each associated with different types of brain activity:

Delta (1-4Hz): Typically seen during sleep. Elevated delta during wakefulness may reflect fatigue, brain injury, or reduced cognitive alertness.
Theta (4-8 Hz): Often linked to drowsiness, daydreaming, and memory encoding. Increased theta may indicate internal focus or reduced external attention.
Alpha (8-13 Hz): Associated with relaxed, wakeful states, especially when the eyes are closed or during quiet rest. A drop in alpha power can reflect increased attention or cogitive load.
Beta (13-30 Hz): Related to active thinking, focus, and motor activity. Higher beta power often reflects engagement, mental effort, or emotional arousal.
Gamma (30+ Hz): Believed to be involved in high-level processing, such as attention, working memory, and integration of information across brain regions. Gamma activity is often subtle and more variable across individuals.

Changes in these bands can reflect shifts in mental or physiological state. By analyzing how power in each band increases or decreases across time or conditions, it's possible to gain insight into cognitive processes like focus, relaxation, or task-related engagement.

File information

filename	C:\Users\CGX\Desktop\Q20v2 Single Condition 5 min Eyes Open Eyes Closed.edf
file size in Mb	7.89
file modification time	Oct 10, 2025, 12:35:08
num channels	26
channel labels	F7, Fp1, Fp2, F8, F3, Fz, F4, C3, Cz, T6, T5, Pz, P4, T3, P3, O1, O2, C4, T4, A2, ExG1, ExG2, ACCX, ACCY, ACCZ, TRIGGER
num timepoints	153000
file length in seconds	306.0
sampling rate	500.0
metadata	(none found)
trim range start	10.0
trim range end	306.0

Temporal Band Powers

This graph shows how brainwave activity changes over time, broken down by frequency band. Higher power in a band reflects stronger activity in that range. This is often linked to different mental states (see Understanding EEG Frequency Bands section). Use this view to spot patterns, shifts, or unusual activity across the session.

Power Bands Session Averages

This section shows the average power in each frequency band across all EEG channels. (See report description at top for a definition of the frequency bands.) These visuals provide a clear overview of the relative presence of each type of brainwave activity throughout the session.

Rather than focusing on where the activity occurs, this summary shows the amplitude of each frequency band in the session overall.

It's a useful first look at the spectral content of the data, helping to highlight which frequency bands may warrant closer inspection in the detailed spatial maps that follow. It's also an easy way to spot which frequency bands show the strongest differences across electrode positions, guiding further interpretation in the topographic maps.

Power Bands Spatial Distribution

The following topographic brain maps show how brainwave activity in each frequency band is distributed across the scalp at each electrode. These heatmaps reveal where different frequency bands of neural activity, i.e., alpha, beta, etc., are strongest or weakest, helping you interpret the spatial organization of the signal. The data is computed from the electrodes and the heatmap showing amplitudes inbetween electrodes is interpolated.

Each colormap is automatically scaled to highlight the spatial patterns unique to that frequency band, rather than show absolute values. Warmer/redder colors indicate regions with higher relative power. These plots are especially helpful for identifying localized patterns, such as frontal theta or posterior alpha, giving you a clearer sense of how brain activity is organized across the session.

Power Bands Cortex Sources

These plots show the distribution of band power across brain regions, projected onto a 3D model of the cortex. Each region of interest (ROI) is color-coded to reflect the relative strength of activity in specific frequency bands, helping you see where in the brain different types of activity are most prominent.

To generate these maps, signals from the EEG channels are mathematically transformed into thousands of underlying source estimates using advanced source reconstruction techniques. This process produces a more anatomically meaningful view of brain activity, moving beyond the scalp to approximate where in the cortex the signals are originating.

The left column displays the full cortical surface, while the right columns show each hemisphere separately for clearer views of deeper and lateral structures. You can click the "Atlas" button to overlay anatomical labels and hover over any region to see its name.

Exploring how different brain regions contribute to overall band power.
Visualizing spatial patterns not captured in scalp-level topoplots.
Linking frequency-specific activity to known functional areas in the brain.